Refrigeration is one of the alcohol industry’s unsung heroes. Though rarely discussed, it plays such a vital role in breweries, cideries, distilleries, and wineries alike.
When storing bottle wine for any extended period of time, it's common knowledge that it must be kept under proper conditions. Typically this is somewhere around 13° C (55° F) and 70% humidity. It makes sense that temperature is important during wine production too, so much so that conservative estimates attribute over 30% of an average winery’s electrical expense to refrigeration.
Just like winemakers, winery refrigeration systems experience their greatest workload during the vintage period.
With more temperature variation depending on the stage of maturation, temperature control is still very important outside of vintage. It will require plenty of refrigeration but may also require heating.
Differences in production requirements create variables that must be considered when choosing refrigeration equipment. Wineries and breweries would be on opposite ends of the spectrum with cideries and distilleries somewhere in between.
Breweries operate on a shorter, more regulated cycle than wineries. The time frame from brewing to bottle is typically a month or less, and the turnover creates a continuous demand for cooling. On the other hand, breweries operate in a broader temperature range than wineries due to the process flow:
Most people consider refrigeration the process of making things cold. Since heat is a form of energy and cannot be destroyed, refrigeration is really the transfer of heat from one place to another.
Commercial refrigeration units, air conditioners, and home refrigerators are all types of mechanical refrigeration systems, which can be simplified into 4 basic components: evaporator, condenser, compressor, and metering device (also known as expansion valve). A refrigerant is cycled through, transferring heat by changing states between liquid and gas:
A typical home refrigerator keeps food cold by using this cycle to transfer heat out of air, which is returned into the refrigerator cabinet to create a cooling effect. Winery refrigeration systems typically use a coolant liquid created using propylene glycol.
Propylene glycol (PG) is considered a food-grade antifreeze. Under normal conditions, it is a colorless, nearly odorless, viscous liquid. Propylene glycol is also used to produce polyurethane and plastics, and interestingly is a common additive in food, beverage, and medicinal products (remember the Fireball Whiskey controversy?). While I’ve never put PG in a product, it’s definitely the first choice for refrigeration needs in the alcohol industry.
Most wineries use a 30-40% glycol mixture for their coolant liquid as it provides several benefits over just normal water:
Refrigeration unit – Unsurprisingly, this is the system’s heart and soul. It must be of sufficient size to keep up with highest load required (more on this later).
Glycol storage vessel – A well-insulated stainless steel tank is ideal as it will minimize heat gain. Logistically, the storage vessel should be in the coolest area possible while remaining near the refrigeration unit, which cycles glycol between itself and the tank. Heat is transferred out of the glycol storage vessel to maintain its set temperature.
Distribution system – This consists primarily of glycol piping and a pump, or pumps depending on demand. The pump pulls glycol from the storage vessel and cycles it through all equipment to be temperature controlled before returning it back to the storage vessel. This process transfers heat back into the glycol storage vessel. The pump(s) should have a manifold with a non-return valve that stops any flow when the pump is not operating. The piping should also be fitted with shut-off valves throughout for regulating glycol flow to specific equipment and for ease of servicing.
Jacketed tanks – Beverage storage vessels specifically designed to control contents' temperature. Glycol circulates through an external cavity, creating heat exchange through the tank wall. Stainless steel tanks are the most common in the alcohol industry. There are several categories of jacketed tanks that effect efficiency, including partially or fully jacketed tanks, which affects the amount of surface allowing heat exchange.
Heat exchanger – A broad term that refers to any equipment that transfers heat between two fluids or gases, these are very useful, if not necessary, for several processes in alcohol production.
Electronics – Electronics are present throughout the system, but these are a bit more complicated.
There are a lot of variables to take into consideration when planning winery refrigeration, but the most important is ensuring the system can sufficiently provide cooling for all processes. Determining exactly what you need can be tricky since no 2 facilities are the same. Consulting a refrigeration specialist is highly recommended before purchasing any equipment.